The invention is in the field of sputtering and, specifically, it relates to a magnetically enhanced sputter coating device.
Sputter coating is a process for coating a substrate by removing material from a target by sputtering and depositing material on a substrate. Sputtering is generally performed by placing a sputtering source and the substrate in a chamber provided with a vacuum pump and gas inlets to maintain a sputtering gas of the appropriate composition and pressure.
A variety of magnetron sputter coating devices are known. Such devices are frequently characterized by the shape of the surface from which material is removed by sputtering. U.S. Pat. No. 4,166,018 to Chapin describes a planar magnetron sputter coating device. U.S. Pat. No. 4,060,470 to Clarke describes a conical magnetron sputtering device. U.S. Pat. No. 4,219,397 to Clarke discloses a cylindrical stepped magnetron device in which the target comprises two concentric but axially offset circular cylinders.
Magnetron sputtering devices are used to deposit a variety of coatings. Frequently, the target material is a metal and the coating is a metal or a reaction product of a metal and a gas such as oxygen or nitrogen. Planar, conical and stepped magnetron sputtering sources are frequently used to deposit thin layers in the manufacture of integrated circuits and other semiconductor products.
The present invention is directed to the solution of several problems inherent in magnetron sputtering devices. First, all such devices have a limited inventory of material which can be sputtered before replacement of the target is required. Second, deposition uniformity must be maintained throughout the life of the target. Third, the deposition rate must be controlled despite variations in the operating voltage and other parameters of the source as the target is eroded.